From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752273Ab3AWUrK (ORCPT ); Wed, 23 Jan 2013 15:47:10 -0500 Received: from mx1.redhat.com ([209.132.183.28]:37882 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750813Ab3AWUrG (ORCPT ); Wed, 23 Jan 2013 15:47:06 -0500 Date: Wed, 23 Jan 2013 14:46:46 -0600 From: Clark Williams To: Steven Rostedt Cc: Peter Zijlstra , LKML , Thomas Gleixner , Ingo Molnar Subject: Re: [PATCH] sched: add a tuning knob to allow changing RR tmeslice Message-ID: <20130123144646.6221097e@redhat.com> In-Reply-To: <1358971778.21576.122.camel@gandalf.local.home> References: <20121108142719.1e0dfc24@redhat.com> <1358971778.21576.122.camel@gandalf.local.home> Organization: Red Hat, Inc Mime-Version: 1.0 Content-Type: multipart/signed; micalg=PGP-SHA1; boundary="Sig_/iKUSPfGrOs_04Ujg78YBmx6"; protocol="application/pgp-signature" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --Sig_/iKUSPfGrOs_04Ujg78YBmx6 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable On Wed, 23 Jan 2013 15:09:38 -0500 Steven Rostedt wrote: > On Thu, 2012-11-08 at 14:27 -0600, Clark Williams wrote: > > Subject: [PATCH] sched: add a tuning knob to allow changing RR timeslice > >=20 > > User wanted a facility simliar to the ability on Solaris to adjust > > the SCHED_RR timeslice value. Add a /proc/sys/kernel scheduler knob > > named sched_rr_timeslice_ms which allows global changing of the SCHED_RR > > timeslice value. User visable value is in milliseconds but is stored as > > jiffies. Setting to 0 (zero) resets to the default (currently 100ms). > >=20 >=20 > Hmm, has this been ignored? >=20 > I guess the real question, is it still needed (or wanted)? >=20 Yes, we've got a couple of customers that have been asking for it.=20 > -- Steve >=20 > > Patch against tip/master, currently 3.7-rc3. > >=20 > > Signed-off-by: Clark Williams > > --- > > include/linux/sched.h | 6 +++++- > > kernel/sched.c | 19 +++++++++++++++++++ > > kernel/sched_rt.c | 4 ++-- > > kernel/sysctl.c | 8 ++++++++ > > 4 files changed, 34 insertions(+), 3 deletions(-) > >=20 > > diff --git a/include/linux/sched.h b/include/linux/sched.h > > index 12317b6..214bf27 100644 > > --- a/include/linux/sched.h > > +++ b/include/linux/sched.h > > @@ -2097,11 +2097,15 @@ static inline unsigned int get_sysctl_timer_mig= ration(void) > > #endif > > extern unsigned int sysctl_sched_rt_period; > > extern int sysctl_sched_rt_runtime; > > - > > int sched_rt_handler(struct ctl_table *table, int write, > > void __user *buffer, size_t *lenp, > > loff_t *ppos); > > =20 > > +extern int sched_rr_timeslice; > > +extern int sched_rr_handler(struct ctl_table *table, int write, > > + void __user *buffer, size_t *lenp, > > + loff_t *ppos); > > + > > #ifdef CONFIG_SCHED_AUTOGROUP > > extern unsigned int sysctl_sched_autogroup_enabled; > > =20 > > diff --git a/kernel/sched.c b/kernel/sched.c > > index cdf9484..c63c3a4 100644 > > --- a/kernel/sched.c > > +++ b/kernel/sched.c > > @@ -120,6 +120,7 @@ > > * Timeslices get refilled after they expire. > > */ > > #define DEF_TIMESLICE (100 * HZ / 1000) > > +int sched_rr_timeslice =3D DEF_TIMESLICE; > > =20 > > /* > > * single value that denotes runtime =3D=3D period, ie unlimited time. > > @@ -9614,6 +9615,24 @@ static int sched_rt_global_constraints(void) > > } > > #endif /* CONFIG_RT_GROUP_SCHED */ > > =20 > > +int sched_rr_handler(struct ctl_table *table, int write, > > + void __user *buffer, size_t *lenp, > > + loff_t *ppos) > > +{ > > + int ret; > > + static DEFINE_MUTEX(mutex); > > + > > + mutex_lock(&mutex); > > + ret =3D proc_dointvec(table, write, buffer, lenp, ppos); > > + /* make sure that internally we keep jiffies */ > > + /* also, writing zero resets timeslice to default */ > > + if (!ret && write)=20 > > + sched_rr_timeslice =3D sched_rr_timeslice <=3D 0 ?=20 > > + DEF_TIMESLICE : msecs_to_jiffies(sched_rr_timeslice); > > + mutex_unlock(&mutex); > > + return ret; > > +} > > + > > int sched_rt_handler(struct ctl_table *table, int write, > > void __user *buffer, size_t *lenp, > > loff_t *ppos) > > diff --git a/kernel/sched_rt.c b/kernel/sched_rt.c > > index c108b9c..799dd09 100644 > > --- a/kernel/sched_rt.c > > +++ b/kernel/sched_rt.c > > @@ -1791,7 +1791,7 @@ static void task_tick_rt(struct rq *rq, struct ta= sk_struct *p, int queued) > > if (--p->rt.time_slice) > > return; > > =20 > > - p->rt.time_slice =3D DEF_TIMESLICE; > > + p->rt.time_slice =3D sched_rr_timeslice; > > =20 > > /* > > * Requeue to the end of queue if we are not the only element > > @@ -1819,7 +1819,7 @@ static unsigned int get_rr_interval_rt(struct rq = *rq, struct task_struct *task) > > * Time slice is 0 for SCHED_FIFO tasks > > */ > > if (task->policy =3D=3D SCHED_RR) > > - return DEF_TIMESLICE; > > + return sched_rr_timeslice; > > else > > return 0; > > } > > diff --git a/kernel/sysctl.c b/kernel/sysctl.c > > index ea7ec7f..10b1129 100644 > > --- a/kernel/sysctl.c > > +++ b/kernel/sysctl.c > > @@ -362,6 +362,14 @@ static struct ctl_table kern_table[] =3D { > > .mode =3D 0644, > > .proc_handler =3D sched_rt_handler, > > }, > > + { > > + .procname =3D "sched_rr_timeslice_ms", > > + .data =3D &sched_rr_timeslice, > > + .maxlen =3D sizeof(int), > > + .mode =3D 0644, > > + .proc_handler =3D sched_rr_handler, > > + }, > > + > > #ifdef CONFIG_SCHED_AUTOGROUP > > { > > .procname =3D "sched_autogroup_enabled", >=20 >=20 --Sig_/iKUSPfGrOs_04Ujg78YBmx6 Content-Type: application/pgp-signature; name=signature.asc Content-Disposition: attachment; filename=signature.asc -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.19 (GNU/Linux) iEYEARECAAYFAlEATDYACgkQHyuj/+TTEp3aAQCg0AktrOXAv5yWje+9WAuPfNiY aJYAoLRaw4AIsBT/XS/Hbxy9G4jGxPdb =O7VD -----END PGP SIGNATURE----- --Sig_/iKUSPfGrOs_04Ujg78YBmx6--